1. Technical Field
The present invention relates to a display apparatus, in particular to a display apparatus for projecting a first window with a first light modulation section and projecting a second window smaller than the first window with a second light modulation section in an overlapping manner.
2. Related Art
Since the past, in work using CAD, simulations, and so on, there have been a lot of cases in which details of a partial image of a display image such as a design drawing is confirmed while confirming the overall picture thereof, and in the case in which a display with a general purpose pixel count such as XGA is used, it is required to repeat zooming in and zooming out of the display image, which incurs decrease in work efficiency. Further, in the case in which the image is zoomed in for confirming the details of the partial image, the overall picture of the image becomes invisible, and therefore, it is difficult to grasp the positional relationship of the partial image with the overall picture.
To cope with such a problem, it is desirable to use a high-resolution display capable of displaying an image pixel by pixel in accordance with a high pixel count image signal to be input thereto. Further, in order for confirming a detailed image, it is desirable that the pixel itself has a size of a visible level, and in that sense, projectors having a somewhat large display screen are one of the most suitable display apparatuses. However, in order for performing display based directly on the image signal with high pixel count, a projector provided with a light valve (e.g., a liquid crystal light valve) corresponding to the input image signal is required, which leads to incurring increase in apparatus cost.
On the other hand, in a display with a large screen, it is natural for the user to view the screen from a position distant from the display to some extent when viewing the overall picture, and from a position close to the display because of limitation in resolution of the eyesight when viewing details thereof.
Therefore, JP-A-2004-70257 (Document 1) discloses a projector capable of projecting a window representing partially detailed information in a screen displaying an overall picture in an overlapping manner, thereby confirming partial details without using a high-resolution display. Further, JP-A-2000-276123 (Document 2) and JP-A-2007-65542 (Document 3) disclose a technology of varying the display resolution in accordance with the observation distance of the user to the screen. For example, the technology of the Document 2 is for detecting the distance between the observer and the screen by a remote controller, and expanding the display image in the case in which the distance is large while shrinking the display image in the case in which the distance is small, thereby keeping the apparent resolution constant. The technology of the Document 3 is for controlling a zoom lens in accordance with the observation distance, thereby always displaying the overall information of the screen with the highest observable resolution for the observer.
In the Document 1 described above, details of the control of the size and the position of the display made by a local projection projector adapted to perform display of a partial detailed image, for example, are not at all disclosed, and therefore, the disclosure thereof is insufficient for coping with the problem described above. Further, in either one of the Document 2 and the Document 3, since the size of the object varies in accordance with the observation distance, the size of the object thus displayed as described above does not vary, which is not suitable for the natural action of viewing the screen from a position closer thereto for confirming the details. Further, the action thereof is adverse to the action of getting closer for viewing the details in such away that the object displayed thereon becomes larger as the observation distance increases and smaller as it decreases, which is not suitable for CAD, simulations, and so on.